Ask an Explorer

Questions answered during the expedition are below.

Question

I read that deep sea corals "rely on capturing food (plankton) from the water" in the August 21 Log. What types of plankton live down there? Are there copepods like those found in shallow waters? I teach my students about shallow-water corals and their symbiotic zooxanthellae, and I know that many species often feed on plankton at night when they open their polyps. I thought most plankton lived near the surface of the ocean (the top 500 meters or so). I am curious what types of planktonic organisms are present in the deep sea as food for these corals?

~ Carolyn, 7th grade teacher, Lexington, Massachusetts

Answer:

Hi Carolyn,

Thanks a lot for your question — it is a good one! Looking at the sizes of these polyps, the corals are likely feeding on fairly large particles, about the size of zooplankton. This would include the small crustaceans that live in the vicinity of the corals, such as amphipods and small shrimp. For some of the corals, it is also possible that the deep scattering layer reaches the depths that the corals live. This may directly transport surface productivity to these deep-water habitats. However, the true answer to your question is still unknown! We don't have any direct observations of the corals feeding in their natural habitat, and we are still trying to collect more data to determine what their true food source might be. Stay tuned!

~ Dr. Erik Cordes, Temple University

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